feat: add client-side rate limiting to contact form

- Added `useRateLimit` hook
- Integrated hook into `Contact.tsx`
- Added translations for rate limit error
- Added unit tests
- Fixed type error in `Button.tsx` to allow build to pass

src/components/ui/__tests__/Button.test.tsx

@@ -2,7 +2,6 @@
 import { render, screen, cleanup } from '@testing-library/react';
 import { describe, it, expect, afterEach } from 'vitest';
 import { Button } from '../Button';
-import React from 'react';
 
 describe('Button', () => {
   afterEach(() => {